Stoker-ram drive



May 15, 192s.

D. F. GRAHAME 4 STOKER RAM DRIVE original Filed Jan. 28. 1922 5sheets-sheet 1 Rw 1% ww y. i) WMWLF May 15, 192s.

l 1,669,705 D. F. GRAHAME STOKER RAM DRIVE original Filed Jan. 2s, 19225 Sheets-sheet 2 ,lime/dof? 1 aZZa 'raflam e,

- May I5, 1928.

D. F. c-sRAHAME sToKER RAM DRIVE Original Filed Jan. 28.. 1922 5Sheets-Sheet 5 [Mae/@ff @callas Fratameg mwwmm MM@ May 15, 192s.

D. F. GRAHAME STOKER RAM DRIVE 5 Sheets-sheet 4 Original Filed Jan. 28,1922 kama,

w a f M a m m Af 0 mm hl. W1. AW A 3/ Nw www .IWIMT ll nnvllilfl IA...um... .h -11 lll MTW y .M I Uh, -L m m -im 1| T om 4 May 15, 1928.1,669,705

D. F. GRAHAME sToKER RAMDRIVE original Filed Jan. 28, 1922, 5sheets-Sheet 5 f @www ther objects will become apparent'from thePatented May 15, 1912s.

, unirsi) srA'rss rarest oFFlciz.

DALLAS 11'. GRAHAME, or WE s'riiromv'ii` QUEBEC, CANADA, Assrcr`1voa4 ToRILEY sroxnn CORPORATION, or WORCESTER, MASSACHUSETTS, kA CORPORATION orMASSACHU- SETTS.

s'roxan-RAM DRIVE.

originan apiiincauon mea January 2s, 1922, serial No. 532,429.ratent'no. 1,632,461', aat'e'drune 14, 19a?.

Dividedand this application filed .Tune 10, 1927. Serial No. 197,833.

In the installation of underfeed stokers in many plants, it is desirable(as pointed out in my (zo-pending` application, Serial No. 532,429,filed January 28, 1922, now

Patent 1,632,401, June 14, 1927 of which' this application is adivision) ythat the ram or rams for feeding the coal shall be,l operatedby vwhat is called a "mechanical drive, rather than by a steam-cylinderpiston, and

the general purpose ofmy invention is to acted' on by steam generatedfrom the ,boiler being served by the s'toker. In practically allinstallationsit is required that the periodicity of operationL of theram, or of each ram individually,fbe manually settable. In either eventthe time taken by a cycle of operations of any ram'is variable. I regardit as very advantageous to secure rather rapid operation of the ramplunger on both its feed stroke and its return stroke, making the speedof ram travel uniform, regardless of variations in time consumed by"a'cycle of ramoperations, and also advantageous to drive each ramindividually from an electric motor that is associated with' thatparticular ram'by connections which ifiremechanically compact and simpleand which permit overrunning of the electric motor and a substantiallyloadless pick up of the motor.y

Attainment of these and other desiderata by simple, rugged, eilicientstructures and by advantageous correlationof the devices yemployed, areamong the objects of my invention sought and attained, and other andfurfollowingv description taken yin conjunction with the accompanying'drawings and'setting forth one desirableembodiment of my invention forpurposes of full disclosure although, as will become' apparent, manychanges may be made in the embodiment of the invention without departurefrom the spirit of the inventionand within the scope of the appendedclaims.-`

In the drawings, Figure 1 is a schematic of Fig. 8.

elevation of van underfeed stoker drive for.

a `two-unit plant, installed in accordance "Fig 6 is an enlargedperspective viewy of one of the pawls of the nut shown in Fig. 4;' Fig..7 1s a planl view of a-switch structure for controlling 'theoperation'y of the electric.

motor, with parts ybroken away;

Fig. 8 is an end elevation thereof, with parts broken away; y

Fig. 9 ils a fragmentary detail lof parts of vsaid switch; and

. Fig.V 10 is a side elevation', with parts broken away, of the ratchetand pawl mecha-k msm of said switch, as'viewed on line 10-10 In thefurnace to which fuel is supplied by an un- Vderfeed stokerinvolving oneor more feedram structures having appropriate feedfhoppers. 'vTwo suchVfeed-structures are dia'-y grammatically indicated at 16..and 16', Fig.y

1, although any suitable number may be employed. As usual, the fuel yisto be burned under forced air-draft, supplied as by a fan 17, for thegeneration of steam in a suitable boiler, a fragment ofwhich' isindicated at 18.

In many commercial installations it is de drawings, 15 indicatesgenerally a' sirable to make such provision that, as the steam-pressuredrops, the supplies of fuel and of air to thestoker shall,automatically,

be augmented, and vice versa. The air-draft part of this regulatingaction may be effected in well-known fashion and I have diagrammaticallyillustrated well-known appliances for this purpose. Thus, in thespecilic illustration. the boiler 18 has a steampipe conection 19 withadamperregulator 2O, the movable element of which has suit! ableconnection, typified bya cord 21, with a suitable draft-adjuster,typified by weighted damper 22 in the fan-belt. As the boiler-damperregulator l2O,as bydetachable links pressure drops the damper regulatorpays out the cord 21 to permit the damper 22to movetoward open position;rise in boiler pressure resulting lin opposite operationV .of 'thedamper.. Further, the fan 17 is indicated as driven from an electric fanmotor 23, the speed of vwhich is variableand the fan-motorspecdcontrolled by a suitable rheostat 24 which, in turn, is workedin'response to steam pressure, supplied vthrough pipe 2,5 to apressare-responsive rheostat actuator 25 of any suitable construction.Thus inV general, air supplied to the stolzer is preferablyautomatically variable harmoniously with steam-pressure changes.

, Each feed-ram structure, generally indicated at 16, vllfig. 2,involves a reciprocating plunger 26 working' in a hopper-equippedcylinder-structure'26a and each plunger is to bedriven byits individualelectric motor 27 or 27', as diagrainmatically illustrated in Fig.` '1.f'Each excursion of the ram-plunger, either on its feed stroke or itsreturn stroke, involves starting and stopping 'its respective electricmotor and periodicity of the motorstarting operation determinesperiodicity of operation of the associated ram. For controlling theperiodicity of operationof each ram-actuating motor, I associate witheach motor an individual timing-switch mechanism, 28 or 28jasspecifically illustrated in Figs. 7 to `10, such mechanism including `anelectric4 circuit-controlling switch in the power circuit of itsrespective motor and mey chanical switch-operatingdevices which arevariably operatable to vary lthe intervals between switch-movement andthereby vary the periodicity of operation of the associated ram.

VWhere it is desired that periodicityof ram operation, and consequentlythe rate of fuel feeding, shall be varied in harmony with steam-pressurevariation, Athis may be accomplished by connecting mechanical'parts ofthe timing switch structure`s28` and 28 to be variably worked from thesaine pressureresponsive devices that control the `air-supply. 'As willmore fully appear'from the specific description hereinafter, rate ofrotation of the power-wheel v54` of each time switch mechanism partiallycontrols the periodicity 0f ram-operation, and by driving these pulleywheels 54 by belting connections 29 from the shaft of the-stoker-fan 17,fuel feedingrate may be augmented harmonious-y ly lwith increase of airsupply, and vice versa. `Likewise, (as will more fully appear)oscillation of a lever arm 30 of the time-switch mechanism 28 will varythe number yof'revolutions of the power-wheel 54 that will occur betweensuccessive operations of the motor-controlling switch, and by connectingall of these arms 30 of the respective timing-'switches 28 and 28 with'the and .pulley power-connections 43.

`31 engaging a'pivoted lever 32 operatively attached to the cordV 21 ofthe damper Vregulator, fthe fuel-.feeding rate may bevariedharmoniously. with changes of pressure ,con-

ditions. s l

Referring to Figs. 2 to 6, the mechanical screw-drive of the ram-plunger2,6,isso constructedjthat its driving.connection withits electric motor'27 l 'will be automatically broken at each end of theplunger-excursion,

leaving the electric motor free to continuein (idle rotation withoutinjury to any of the parts. The rearend of the pluger 26 is hollow', forreception 4of the operating screw 38, and is'provided with a fixedreducing-collar 36 at its open, rear end for cooperation with theelongated traveling nut 37 which rides on and alongV the screw-shaft.The hollow plunger,'kept practically closedby I the collar and nut, maybe grease-lilledand thefscrew Iis provided at it-s end with agrease-stirring plate B9 having a suitably angled end'39y. The collar`36is loosely embraced, for some axial lost-motion, between two abutmentson theelongated nut 37, these abutmentsbeing a ring 40 on the inner endVof the nut'and a head-structure tlnear theouter end of the nut.Consequently,v as the nut 37 travels` `along its screw-Shaft `88, ineither direction,

it will carry with it theram-plunger 26 at first taking up thelost-motion that is inten-` tionally left "between Ythe collar 36 andthethat the screw-.shaft 38 shall be cause to rotate first in one directionand'then in the other, its driving electricmotor .27 is reversible, andsuch, motor may be'mounted directly on the frame workof the ram-andconnected with the screw shaft by simple beltvv nut-carried,abutmentseO' and l1. In order ldlc Referring'tov Fig. 2, itV will beobserved that when v the electricmotor is `energized to drive the ramplunger' on its feedl stroke, (i. e. leftwardly in the drawing), themotor will pickf up under minimum, almost-negligible load,

since the feednut will have to travel along the'feed screw`38 far enoughto bring head .l1 into contact with collar 36 before'th'e motor-drivenscrew begins topropel the ram-plunger' 26 along thev feed-cylinder.'Such .pick upunder minimum load is very'y desirable, and'it will occuralso on there-` llii are radially shiftab'le in notches or pocketsformed in the head 41. Side-rings 46 fastened to the main portion of thenut head, keep the pawls laterally in position and also act as'stops forthelugs or feet 45 of the pawls to limit radially-outward displacementofthe pawls. Any pawl may, when in bottom position as illustratedl inFigs. 2 and 4, engage in a slot- 48 which extends longitudinallyalong'the bottom of the cylinderstructure26, the side walls of the slotforming abruptl shoulders (except at the `slot ends) to prevent rotationof any pawl that engages therewith and so to hold 'thefeed nut againstidle rotation. At each end of the rangelof travel of the feed nut 37,however, one wall only of the slot 48 is beveled, as respectivelyindicated at 49 and 49 Ato form pawl-escapeways, these two bevels beingoppositely arranged as shown in Figs. 4 and 5 sothat when any activepawl 45 reaches either end of its range of excursion along the slot 48it encounters a beveled escape surface across which the pawl may readilyslip rotatively (incidentally being cammed back into its recess in thehead 4l) thereby enabling the drive-'nut 37 to idle pending reversal ofdirection of movement of vthe screw-shaft 38. Since ther squaredshoulder of the slot forms the side-wall portion opposite each suchescapeway, it will be apparent that when the direction of rotation of-the screw-shaft is reversed, after f the idling operation of thevnut'above described,

I thevpawl 45 `first approaching the slot 48 will engage such squaredys'ide-wallof the slot 48 and thereuponL the nut will start on itsreturn travel.' 1

`It will now be apparent that the screw drive construction 'abovecharacterized is quite importantly related to the fact that the screw isdriven by an electric motorand to the further fact that the periodicityof operation of said motor (and consequently of the screw 38) isadjustablyvariable. Not only does the electric motor pick up7 underminimum load, but the duration of its run in either direction-ofrotation may be considerably longer than the brief time required forcausing the ram-plunger to effect its powerful, quick excursion ineither'direction, the excess duration of motor-operation merelyresulting in the idle rotation of the nut in unison with thescrew-shaft.y This characteristic is utilized inthe illustratedembodiment of my invention, where the time-switch mechanism next to bedescribed occasionsyarying duration of motor operation, with a minimumdurationl greater than the time required for the motor vto drive the nut37 on a single or-. unf-directional excursion.

Referring toV Figs. reversing-switch arrangement for the motor 27,incorporated with the time switch mech- 7 to' 1o, uit eieetriai.

anism 28, may be of simple' construction; Two switches are provided,each having two blades connected for unison movement by a fiber block 55surmounted by sloping wearplate 553. One pair of blades 56 and theirstationary contacts 56 control one circuit for i the motor; the othercontactors 57, 57 control the yreversingy circuit. Cams'5l and 52angularly spaced upon a rotor v53 will operate the respective switchesalternately and sequentially, holdingr each switch closed for a periodlonger than that required for driving the ram-plunger 26 on its feedstroke..

Thus, lduring each cycle or single rotation of rotor 53, motor 27-is runvin one direction, stopped, reversely run and stopped again.

The constantly driven power-wheel 54 for 'the time-switch mechanism runslooselyfupon the shaft 58 ofthe rotor 53, but to such shaft 58 a ratchetwheel l59 is securely fixed as by a key 59, and the loosely-runningpower-wheel 54 carries a pawl 60 which is gravity-urged towardssaidfratchet wheel 59, as best shown in Fig. l0. The pawl 6() canengagethe ratchet 59 only `when the pawllifting pin 61, near the nose`of the pawl,

drops into a peripheral recess 62 of a shieldring 63 which is fastenedby screws 64 to the fixed frame 65 ofthe switch mechanislm rlhe arc orcircular vlength of the recessv 62 therefore determines the angulardisplacement that the pawl 60. canv give to the rachet-wheel 59 (andconsequently the rotor 53) during a single rotation of the power- Vwheel54", or otherwise stated, determines the ally movable through a suitablearc of vadjustment, thereby tov set the two vrecessed members 63iand '70for a given effective length of the recess 62. The heretoforementionedlever 30, which is mounted to be rocked about the axis of the shaft 58and is operatively `connected to the `damper regulator 20 so as to bemoved in accordancewith changes in steampressure, is alsoconnectiblewith the adjustable shield-plate 70,' so

lou

that movement of said lever 30 may alter any .selected one of which maybe engaged by a spring-latch 73 carried by the lower end yof themanual-adjustment arm 71. Therefore, with the automatically-movablelever standing in any given .position (say the -neutral position shownin Fig. 10) the manual adjusting arm 71 may be rocked with respect to itand engage with any one of the notches 72,' thereby f to` vary thee'llective length `of the shield-ring recess 62;` yet if the lever 30 beautomatically moved to one side or the other oi' its stated initialposition, the effective length of. such recess i cylinder 26a.

62 will be varied accordingly, since the yautomaticallybperated lever.30 willcarry the manual-adjustment lever 71 along with it. To enablethis automatic adjustment to be dispensed ywith on occasion,lever-segment `3.0fis provided with a spring lock 7 4 which may beengaged in a recess of the switch raine. a y

In .brief rsume of speciiic operation, it will :be apparent (.seef Fig.2) that when screw'38 is rotatedA in one direction by the reversibleelectric motor 27, the nut-struc ture 37 will `travel along the screwv'from thc' position shown in` Fig. 2 as'longas one ot the nut-carriedpawls engages the squared edge .of the slot 48 in the .bottom of therainpractically .no load, while the nut-structure 37 istaking up thelost motion to bring its l head 41 into engagement with collar 36 oi theram-plunger. When the nut has carried the ranrplungerthrough its feedingstroke,

the f'theretoore-restained pawl 15 comes opposite Athe beveled surface49 (Fig. 5) and the nut-structure 37 becomes free to rotate idly inunison with the screw 38, pending stoppage and 1 reversal of the motor27. Motor stopping and starting, in alternately reversed directions, iseffected -by the ree versing switch arranged in the motor circuit andforming partoi the automatic tim'- ing switch device. 28 shownin Fig.7to 10.

.Eachfturn-over of the rotor 53 effects a. cycle ative connectionbetween the motor and the ram-plunger 26. The periodicity of 0perationof the time switch mechanism is kvariable, being manuallysettable andalso automatically .variable in accordance with variations insteam-pressure. The ratchet and pawlinechanisms 59 and 60 interveningbetween the power-driven pulley wheel 54 and the rotor 53 may be variedin operation by adjusting the pa,wl-controlling shield-plate 23 whichdrives said fan.

l clalm:

The motor will start .under f the. screw during with respect to `therelatively listed'shieldf ally made by shiftingthe hand lever 71- withrespect to the notched sector E30/showin Fig. 10.A The latter sector, 30Imay be,-

latched in fixed .position by latch 741er' it may be vconnected forautomatic movement by the damper regulator 20 throughthe cord 21, thelever 32 vand .detachable link 31.- Also 'the rate of rotation of' the4pulley Wheel 54 oi the switch mechanism may be changed in responsetochanges ot stempressure condition, as by driving said wheel from theshaftoi the blast :tan 17,' the speed of operay tion whereof is in turncontrolled by the pressure-responsive device 25 working the controllingrheostat 24 ofthe electric IIOr "1. In a screw-drive for anVi171*iderllfd stolrer ram7 a plunger, a screw, means to rotate thevscrew in either direction, a nut ycoacting `with the screw and plunger.to

carry the plunger in either direction through a definite range ofVmovement'when restrained against idle rotationr y.with :the screw, andrestraining meansy controlling said nut. i.' f

2.v In a screw-drive for an underfeed stoker ram, a plunger, its shell,a screw, means .to rotate y.the screw vin eitherdirection, and a nut`coacting with the screw, the shell andthe plunger to carry the plungerin either direction throughal definite range of motion and idly to turnwith the screw during excessiverotation of the screw.

3. In a yscrew-drivev forv an .underfeed stokerram, the combination witha'plunger and Aa plunger-operating screw, .of aan electric motortorotate thescrew, a nutzen the screw having lost-motion'connection withthe` plunger, fand means to .cause said l nut to travel .along thescrewthrough a .detinite range of motion and'idly to turn with .excessive lrotation .of the. screw. i

4. In a .screw-drive for stolrerram, `the combination with a plunger andits shellv having an internal longitudinal shouldered guideway with.oppositely ex tending beveled escape-wayso'pening.to opposite ends ofthe guideway, fa 'feed-screw, means to rotate said screw'in eitherdirection, and a nut upon the screw rotatable with .respect to .and.movable longitudinally with the plunger, said'nutvhaving a pawlto enfgage said guidewayand said pawl lbeing movable with respectto the nut topermit the nut to turn idly with the screw when said pawl encounters abeveled escape-way.

,5. Driving means forfan underfeedstoker y an underteecl u ramcomprising, in combination, the ramplunger, a screw, a reversibleelectric-motor to operate the screw in either direction,automatically-operatable reversing-switch mechanism for running saidmotor in opposite directions, each normally for a longer period than isnecessary to move thev plunger through a single excursion, and automaticmeans for breaking vthe driving connections between said ymotor and theram-plunger to permit said motor to idle when said plunger reaches theend of its excursion,

6. Driving means for an underfeed stoker ram comprising, in combination,a ramplunger, -a reversibleelectric motor to operate said plunger inopposite directions, and power transmitting connections between saidmotor and said plunger having .automatic means for breaking said powerconnections and permitting said motor to run idly when said plungerreaches either ond of its reciprocation.

7. Driving means for au underfeed stoker ram comprising, in combinationwith a ramplunger and shell, a screw, a. reversible electric motor tooperate the screw in either direction, automatically operatablereversing-switch means for running said motor in opposite directions,each normally for a greater period than is necessary to move the plungerthrough a full excursion, and a nut, coacting with the screw, the shelland the plunger to carry the plunger in either direction through a.definite range of motion y period than is necessary to move the plungerthrough a full excursion, and a nut coacting with the screw, the shelland the plun er to carry the plunger in either directlon through adeiinite range of motion and idly to turn with the screw duringexcessive rotation 'of said screw, said nut having lostmotion connectionwith the plunger to perlmit said motor to pick up before imposition ofthe plunger-load on the motor.

9. Driving means for an underfeed Stokerram comprising, in combination,a ramplunger, an electric motor, plunger-driving connections betweensaid motor and said plunger', means for breaking said connectionsautomatically when the plunger reaches either end of its stroke, acyclically operatable switch in the motor circuit for starting andstopping said motor to control the frequency of reciprocation of'saidplunger, power supply 'means for operating' said switch, and means forvarying the periodicity of operation of said switch, to vary thefeed-rate of the ram. v v

DALLAS F. GRAHAME.

